fix: copy buffers

[ronag]

Fixes: #710

[ronag]

@indutny

[ronag]

Not sure if there is a faster way to copy which doesn't not involved creating a temporary Buffer.

[indutny]

I think this should be about as fast as it can be, but you could experiment by creating a buffer from buffer something like wrapping your previous Buffer.from() calls with another Buffer.from(). The benefit of latter is that you don't do unsafe allocations.

[ronag]

@indutny: Another question. Would it be possible for wasm_on_header_ and wasm_on_body to instead point into the buffer passed to execute? That way no copy would be required. The exact same data should already be there, or alternatively could be written there.

[indutny]

@ronag that buffer is relative to the input of the execute already. I think the problem is that you copy it into wasm memory and so you get back a slice of the very same memory you copied it to. Not sure if there is a way to pass data to wasm without copying. Perhaps shared buffers?

[mcollina]

I have a feeling that this unwinds any gain we got by using buffers for Headers, would not be better to revert?

Anyway LGTM

[ronag]

I have a feeling that this unwinds any gain we got by using buffers for Headers, would not be better to revert?

Anyway LGTM

I still haven’t given up. I think I can sort this as zero copy still.